If $F$ is an $s$-spectrum, then what does the functor $\sum_s^n F$ mean for negative values of $n$?

Question

I have been learning motivic homotopy theory from these notes and on page 151 (page 5 of the pdf), the author uses $\sum_s^n F$ where $F$ is an $s$-spectrum. For non-negative $n$, I figured that this meant "take the smash product of $F$ with the $n$-fold smash product of $S^1_s$", but I cannot make sense of it for negative values of $n$.